Quantifying phase noise of an oscillator is important in many applications like communications and radar, for instance in the automotive sector. In certain cases, the signal to be measured is modulated, in particular phase modulated, which makes traditional phase noise measurement methods impossible, since these assume a constant frequency or continuous wave (CW) oscillation. In time domain, the phase noise is often referred to as “jitter”.
In applications where the signal is modulated in phase and/or frequency, e.g. for frequency modulated continuous wave (FMCW) radar applications, and the unmodulated signal is either not directly accessible for measurement due to tight integration of components or if the adverse effects of a frequency and/or phase modulator on the phase noise need to be taken into account, traditional CW measurement methods are not sufficient.
Therefore, there is a need for a method as well as for a measurement device capable of reliably analyzing phase noise in a modulated signal.